1. Field of the Invention
The invention relates to transdermal delivery systems which allow for the variable dosage and or moltiple dosage of medicament in a patient controllable or pre-set format.
2. Description of the Related Art
Transdermal drug administration has recently come to the forefront as a useful route for continuous dosing of useful drugs where other means of administration are either discontinuous, labor intensive or where other routes present absorption or inactivation problems. Whereas per os administration has been time honored i.e. "a teaspoonful three times a day", such unit dose administration was subject to erratic blood levels of the actives due to non-uniform absorption from the gut due to other gut contents or inactivation of the drug actives by the digestion process or the normal action of the liver.
In addition, the need for active periodic administration i.e. three times a day, required active and willing participation by the patient or in home or hospital settings by the caregiver i.e. mother or nurse.
All these shortcomings are obviated by transdermal application where possible, of the drugs. A patch is adhered to a clear area of the skin and the drug is continually absorbed through the skin into the bloodstream for systemic distribution.
The skin is particularly useful as it presents large areas for drug administration, as the skin is the largest organ of the body. The utility of such a mode of administration has been demonstrated to those skilled in the art, as described, for example, in my copending application Ser. No. 865,309.
Almost any drug, at least to some degree, can be administrated transdermally. Reference is herewith had to U.S. Pat. Nos. 4,917,676, 3,598,122; 3,598,123; 3,742,951; 3,797,494; 3,948,254; 3,996,734; 4,284,444; and 4,597,961. Examples of such pharmacological actives include administration of antibacterial such as the penicillins, tetracyclines, second and third generation cephalosporins, chlor-amphenicol sulfonamides; sedatives and/or hypnotics, such as barbiturates, carbromal, antijussives such as codeine and dextromethorphan; anti-anxiety drugs such as the benzodiazepines including diazepam, buspirone; psychostimulants such as imipramine amitriptyline and other tricyclic anti-depressants; anti psychotic drugs and tranquilizers such as lithium, chlorpromazine and haloperidol, reserpine, thiopro-pazate; Parkinsonism control agents such as bromotriptine, percolide, the anticholmergics including benzotropine, pro-cyclidine, amantadine (also an antiviral); hormones and hormone antagonists and agonists, including adrenocortico-steroids; insulin, androgenic steroids, estrogenic and pro-gestrogenic steroids, thyroxin and its agonist 5-FU(fluoro-uracil), tamoxifen; antipvretics and analgesics such as aspirin/acetaminophen and other non-steroidal anti-inflammatory drugs (NSAID), analgesics based on morphine; morphine antagonists; vasodilating agents such as nitro-glycerine, isorbide dinitrate; alpha beta-blockers and other cardioactive drugs; antimalarials; anti-histamines and anti-cholinergics including atropine hyoscyamine or methscopalo-mine (for motion sickness; weaning agents such as nicotine for addiction to tobacco; and antiasthmatic bronchodilators such as formoterol; and combinations of such pharmaceutical actives.
Of course, while feasible, not all of these actives have yet been completely tested for efficacy by transdermal administration but many are under vigorous scrutiny. Other actives at this time are not economically viable for such administration, as the cost of full safety testing is too great for the specific number of patients involved.
As can be seen from this background discussion and the history of this type of medication, it is apparent that application by transdermal patch is a useful form for the administration of medication. However, a single dose per patch does not allow for clinical variations through adjustable dosage selection.
Various techniques of transdermal administration of drugs have been disclosed in the art. However, the prior art does not allow for variable dosage within a single patch or for sequential dosage within a single patch.